A high-strength sputtering target for forming a protective film for an optical recording medium, obtained by sintering a mixed powder containing, in mol %, 10 to 70% of a zirconium oxide or hafnium oxide and 50% or less (over 0%) of silicon dioxide, and 0.1 to 8.4% of yttrium oxide as necessary, and the remainder containing aluminum oxide, lanthanum oxide, or indium oxide and inevitable impurities, wherein a complex oxide phase of Al6Si2O13, La2SiO5, or In2Si2O7 is formed in a base of the target.
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1. A high-strength sputtering target for forming a protective film for an optical recording medium, obtained by sintering a mixed powder consisting of, in mol %, 10 to 70% of zirconium oxide, and 50% or less and more than 0% of silicon dioxide including an amorphous silicon dioxide, and the remainder containing indium oxide, wherein a complex oxide phase of In2Si2O7 is formed in a base of the target.
4. A high-strength sputtering target for forming a protective film for an optical recording medium, obtained by sintering a mixed powder consisting of, in mol %, 10 to 70% of zirconium oxide, 0.1 to 8.4% of yttrium oxide, and 50% or less and more than 0% of silicon dioxide including an amorphous silicon dioxide, and the remainder containing indium oxide, wherein a complex oxide phase of In2Si2O7 is formed in a base of the target.
7. A method for producing a high-strength sputtering target with a complex oxide phase of In2Si2O7 formed in a base of the target, for a protective film for an optical recording medium comprising the steps of:
press molding a mixed powder consisting of, in mol %, 10 to 70% of zirconium oxide, and 50% or less and more than 0% of silicon dioxide, and the remainder containing indium oxide; and
sintering said mixed powder in an oxygen atmosphere at 1300° C. or higher to form the complex oxide phase of In2Si2O7 in the base of the target,
wherein, the silicon dioxide in the mixed powder includes an amorphous silicon dioxide.
10. A method for producing a high-strength sputtering target with a complex oxide phase of In2Si2O7 formed in a base of the target, for a protective film for an optical recording medium comprising the steps of:
press molding a mixed powder consisting of, in mol %, 10 to 70% of zirconium oxide, 0.1 to 8.4% of yttrium oxide, and 50% or less and more than 0% of silicon dioxide, and the remainder containing indium oxide; and
sintering said mixed powder in an oxygen atmosphere at 1300° C. or higher to form the complex oxide phase of In2Si7O7 in the base of the target,
wherein, the silicon dioxide in the mixed powder includes an amorphous silicon dioxide.
2. The high-strength sputtering target according to
3. The high-strength sputtering target according to
5. The high-strength sputtering target according to
6. The high-strength sputtering target according to
8. The method for producing a high-strength sputtering target according to
9. The method for producing a high-strength sputtering target according to
11. The method for producing a high-strength sputtering target according to
12. The method for producing a high-strength sputtering target according to
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This is the U.S. National Phase Application under 35 U.S.C. §371 of International Patent Application No. PCT/JP2007/061643 filed Jun. 8, 2007, which claims the benefit of Japanese Patent Application No. 2006-159303 filed Jun. 8, 2006, both of which are incorporated by reference herein. The International Application was published in Japanese on Dec. 13, 2007 as WO2007/142333 A1 under PCT Article 21(2).
The present invention relates to a high-strength sputtering target (hereinafter, referred to as “target”) for forming a protective film for an optical recording medium which is capable of recording, reading out, repeatedly recording and reading out, and erasing information using a laser beam.
It is generally known that protective films (hereinafter including both lower and upper protective films) for an optical recording medium such as a laser disk or the like typically include 20% of silicon dioxide (SiO2) with the remaining part being zinc sulfide (ZnS). This protective film is known to be obtained by carrying out sputtering with the use of a target for forming a protective film for an optical recording medium, i.e., a ZnS—SiO2 based hot-press sinter which includes 20% silicon dioxide (SiO2) with the remaining part being zinc oxide sulfide (ZnS).
However, such a protective film prepared by using a target composed of a ZnS—SiO2 based hot-press sinter causes a problem in that repeatable re-recording performance deteriorates when a laser beam is irradiated to a recording layer to repetitively perform re-recording since S in ZnS of a target composed of a ZnS—SiO2 based hot-press sinter diffuses in the recording layer. Consequently, development of a protective film containing no S has been carried out. Examples of a protective film containing no S, as follows, are known where values are in mol %.
(i) A protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of zirconium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing aluminum oxide and inevitable impurities.
(ii) A protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of hafnium oxide, 50% or less (over 0%) of silicon dioxide and the remainder containing aluminum oxide and inevitable impurities.
(iii) A protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of zirconium oxide, 0.1 to 8.4% of yttrium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing aluminum oxide and inevitable impurities.
(iv) A protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of zirconium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing lanthanum oxide and inevitable impurities.
(v) A protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of hafnium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing lanthanum oxide and inevitable impurities.
(vi) A protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of zirconium oxide, 0.1 to 8.4% of yttrium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing lanthanum oxide and inevitable impurities.
(vii) A protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of zirconium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing indium oxide and inevitable impurities.
(viii) A protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of hafnium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing indium oxide and inevitable impurities.
(ix) A protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of zirconium oxide, 0.1 to 8.4% of yttrium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing indium oxide and inevitable impurities.
In addition, a target for forming protective films for an optical recording medium which have compositions described in the foregoing (i) to (ix) has been developed. This target has the same composition as the protective films for an optical recording medium mentioned in (i) to (ix) above (refer to Japanese Patent Application Laid-Open No. 2005-56545).
The target employs the oxide powders mentioned in the foregoing (i) to (ix) as a raw powder. The raw powders are mixed at a predetermined ratio and combined to prepare a mixed powder. The mixed powders are molded and baked in air or an oxidative atmosphere such as an oxygen atmosphere, thereby producing the targets.
In targets produced by mixing oxide powders prepared as in (i) to (ix) as raw powders at a predetermined ratio and combining into mixed powders, followed by molding and baking the mixed powders in an oxidative atmosphere under normal conditions, cracks occur during high-power sputtering, and thus formation of a protective group for an optical recording medium cannot be efficiently achieved.
An object of the present invention is to provide a high-strength target for forming a protective film for an optical recording medium in which cracks do not occur even in high-power sputtering.
The inventors of the present invention have carried out extensive studies to produce a high-strength target for forming a protective film for an optical recording medium without producing cracks even in high-power sputtering. As a result, the following results are obtained.
(a) As for a sputtering target for forming a protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of zirconium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing aluminum oxide and inevitable impurities; a sputtering target for forming a protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of hafnium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing aluminum oxide and inevitable impurities; or a sputtering target for forming a protective film for an optical recording medium produced by sintering a mixed powder containing 10 to 70% of zirconium oxide, 0.1 to 8.4% of yttrium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing an aluminum oxide and inevitable impurities; a target having a structure in which a complex oxide phase of Al6Si2O13 is formed in a target base has further improved density and strength. Thus, cracks do not occur in the target during high-power sputtering.
(b) As for a sputtering target for forming a protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of zirconium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing lanthanum oxide and inevitable impurities; a sputtering target for forming a protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of hafnium oxide, and 50% or less (over 0%) of a silicon dioxide, and the remainder containing a lanthanum oxide and inevitable impurities; or a sputtering target for forming a protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of zirconium oxide, 0.1 to 8.4% of yttrium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing a lanthanum oxide and inevitable impurities; a target having a structure in which a complex oxide phase of La2SiO5 is formed in a target base has further improved density and strength. Thus, cracks do not occur in the target during high-power sputtering.
(c) As for a sputtering target for forming a protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of zirconium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing indium oxide and inevitable impurities; a sputtering target for forming a protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of hafnium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing an indium oxide and inevitable impurities; or a sputtering target for forming a protective film for an optical recording medium produced by sintering a mixed powder including 10 to 70% of zirconium oxide, 0.1 to 8.4% of yttrium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing an indium oxide and inevitable impurities; a target having a structure in which a complex oxide phase of In2Si2O7 is formed in a target base has further improved density and strength. Thus, cracks do not occur in the target during high-power sputtering. A target having a structure in which a complex oxide phase of In2Si2O7 is formed in a target base gives more remarkably improved density and strength as compared to a target having no complex oxide phase of In2Si2O7.
The present invention has been made on the basis of these study results.
(1) According to a first embodiment of the invention, there is provided a high-strength sputtering target for forming a protective film for an optical recording medium, obtained by sintering a mixed powder including, in mol %, 10 to 70% of zirconium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing an aluminum oxide and inevitable impurities; the target has a structure in which a complex oxide phase of Al6Si2O13 is formed in a target base. More preferably, the content of the zirconium oxide is in the range of 20 to 50 mol %, and the content of the silicon dioxide is in the range of 10 to 30 mol %.
(2) According to another embodiment of the invention, there is provided a high-strength sputtering target for forming a protective film for an optical recording medium, obtained by sintering a mixed powder including, in mol %, 10 to 70% of hafnium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing aluminum oxide and inevitable impurities; the target has a structure in which a complex oxide phase of Al6Si2O13 is formed in a target base. More preferably, the content of the hafnium oxide is in the range of 20 to 50 mol %, and the content of the silicon oxide is in the range of 10 to 30 mol %.
(3) According to another embodiment of the present invention, there is provided a high-strength sputtering target for forming a protective film for an optical recording medium, obtained by sintering a mixed powder including, in mol %, 10 to 70% of zirconium oxide, 0.1 to 8.4% of yttrium oxide, and 50% or less (over 0%) of a silicon dioxide, and the remainder containing an aluminum oxide and inevitable impurities; the target has a structure in which a complex oxide phase of Al6Si2O13 is formed in a target base. More preferably, the content of the zirconium oxide is in the range of 20 to 50 mol %, and the content of the silicon oxide is in the range of 10 to 30 mol %.
(4) According to another embodiment of the present invention, there is provided a high-strength sputtering target for forming a protective film for an optical recording medium, obtained by sintering a mixed powder including, in mol %, 10 to 70% of zirconium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing lanthanum oxide and inevitable impurities; the target has a structure in which a complex oxide phase of La2SiO5 is formed in a target base. More preferably, the content of the zirconium oxide is in the range of 20 to 50 mol %, and the content of the silicon oxide is in the range of 10 to 30 mol %.
(5) According to another embodiment of the present invention, there is provided a high-strength sputtering target for forming a protective film for an optical recording medium, obtained by sintering a mixed powder including, in mol %, 10 to 70% of hafnium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing lanthanum oxide and inevitable impurities; the target has a structure in which a complex oxide phase of La2SiO5 is formed in a target base. More preferably, the content of the hafnium oxide is in the range of 20 to 50 mol %, and the content of the silicon oxide is in the range of 10 to 30 mol %.
(6) According to another embodiment of the present invention, there is provided a high-strength sputtering target for forming a protective film for an optical recording medium, obtained by sintering a mixed powder including, in mol %, 10 to 70% of zirconium oxide, 0.1 to 8.4% of yttrium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing lanthanum oxide and inevitable impurities, the target has a structure in which a complex oxide phase of La2SiO5 is formed in a target base. More preferably, the content of the zirconium oxide is in the range of 20 to 50 mol %, and the content of the silicon oxide is in the range of 10 to 30 mol %.
(7) According to another embodiment of the present invention, there is provided a high-strength sputtering target for forming a protective film for an optical recording medium, obtained by sintering a mixed powder including, in mol %, 10 to 70% of zirconium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing indium oxide and inevitable impurities; the target has a structure in which a complex oxide phase of In2Si2O7 is formed in a target base. More preferably, the content of the zirconium oxide is in the range of 20 to 50 mol %, and the content of the silicon oxide is in the range of 10 to 30 mol %.
(8) According to another embodiment of the present invention, there is provided a high-strength sputtering target for forming a protective film for an optical recording medium, obtained by sintering a mixed powder including, in mol %, 10 to 70% of hafnium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing indium oxide and inevitable impurities; the target has a structure in which a complex oxide phase of In2Si2O7 is formed in a target base. More preferably, the content of the hafnium oxide is in the range of 20 to 50 mol %, and the content of the silicon oxide is in the range of 10 to 30 mol %.
(9) According to another embodiment of the present invention, there is provided a high-strength sputtering target for forming a protective film for an optical recording medium, obtained by sintering a mixed powder including, in mol %, 10 to 70% of zirconium oxide, 0.1 to 8.4% of yttrium oxide, and 50% or less (over 0%) of silicon dioxide, and the remainder containing indium oxide and inevitable impurities; the target has a structure in which a complex oxide phase of In2Si2O7 is formed in a target base. More preferably, the content of the zirconium oxide is in the range of 20 to 50 mol %, and the content of the silicon oxide is in the range of 10 to 30 mol %.
For producing a high-strength sputtering target for forming a protective film for an optical recording medium according to the present invention, zirconium oxide powder, yttira stabilized zirconia powder, hafnium oxide powder, amorphous silicon dioxide powder, aluminum oxide powder, lanthanum oxide powder, and indium oxide powder are employed as raw powders. These raw powders are combined and mixed to give compositions mentioned in (1) to (9), thereby preparing mixed powders. The mixed powders are press molded, after which the molded bodies are actively sintered at 1300° C. or higher, which is higher than the usual sintering temperature, in an oxygen atmosphere, thereby producing targets.
When producing a high-strength sputtering target for forming a protective film for an optical recording medium according to the present invention, it is crucial to use an amorphous silicon dioxide powder as the raw powder, to adopt an oxygen atmosphere, and to conduct baking at a temperature of 1300° C. or higher. If a crystalline silicon dioxide power is used, warpage occurs in the produced target, which is not preferable as the strength decreases. Furthermore, zirconium oxide powder to be used as the raw powder may be a stabilized or partially-stabilized zirconium oxide powder. As such the stabilized or partially-stabilized zirconium oxide powder, for example, there is a zirconium oxide powder containing 1 to 12 mol % of Y2O3.
A target for forming a protective film of an optical recording medium according to the invention can be made larger since the strength of the protective film is further improved. Moreover, since cracks do not form in the target even under a high-power sputtering, a protective film for an optical recording medium can be formed more efficiently.
Hereinbelow, the target for forming a protective film for an optical recording medium according to the present invention will be described in more detail with reference to Examples.
The following powders were prepared as the raw powders: ZrO2 powder having an average particle diameter of 0.2 μm and a purity of 99.99% or higher, HfO2 powder having an average particle diameter of 0.2 μm and a purity of 99.99% or higher, SiO2 powder having an average particle diameter of 0.2 μm and a purity of 99.99% or higher, SiO2 powder having an average particle diameter of 1 μm and a purity of 99.99% or higher, In2O3 powder having an average particle diameter of 0.5 μm and a purity of 99.99% or higher, Al2O3 powder having an average particle diameter of 0.5 μm and a purity of 99.99% or higher, and La2O3 powder having an average particle diameter of 0.5 μm and a purity of 99.99% or higher. In addition, a stabilized ZrO2 powder containing 3 mol % of Y2O3 was also prepared.
The ZrO2 powder, amorphous SiO2 powder, crystalline SiO2 powder, and Al2O3 powder were weighed to give the composition shown in Table 1 and uniformly mixed by a Henschel mixer. Subsequently, the mixed powder was press-molded, after which the obtained molded body was baked under the conditions given in Table 1, thereby producing an inventive target 1 and a conventional target 1, both of which had a diameter of 200 mm and a thickness of 6 mm and included 30% of ZrO2, and 20% of SiO2, and the remainders containing Al2O3. The cross sections of the target 1 of the present invention and the conventional target 1 were polished and observed through X-ray diffraction and an EPMA to determine whether or not a complex oxide phase of Al6Si2O13 was formed in the bases of the targets. The results of which are given in Table 1. Furthermore, the density and flexural strength of the target 1 of the present invention and the conventional target 1 were measured. The results are shown in Table 1.
Then, the produced target 1 of the present invention and the produced conventional target 1 were mounted in a direct current magnetron sputtering system, in a state of being soldered with a water-cooled backing plate made of oxygen-free copper. First, the inside of the system was evacuated to be 1×10−6 Torr or less using a vacuum air exhauster. Then, an Ar gas was introduced into the system so as to give a pressure of sputtering gas of 1.5×10−3 Torr. A polycarbonate substrate with a thickness of 0.6 mm was disposed at an interval of 70 mm, i.e., the interval of the targets. In this state, a direct current power, i.e., a sputtering power of 9 kW which was higher than the norm, was applied, and protective films for an optical recording medium, having a thickness of 50 nm, were formed on a surface of the polycarbonate substrate, using the target 1 of the present invention and the conventional target 1, respectively. Here, observation to determine whether or not cracks are formed in the targets was made. The results of which are shown in Table 1.
TABLE 1
Existence or
Properties of Target
Nonexistence
Existence or
Conditions of Baking
of Complex
Nonexistence
Composition of Raw Powder (mol %)
Tem-
Keeping
Oxide of
Flexural
of Cracks
Amorphous
Crystalline
perature
Time
Al6Si2O13 in
Density
Strength
during
Target
ZrO2
SiO2
SiO2
Al2O3
Atmosphere
(° C.)
(h)
Target Base
(%)
(MPa)
Sputtering
Present
1
30
20
—
remainder
oxygen
1400
7
Existent
96
275
Nonexistent
Invention
Conventional
1
30
—
20
remainder
air
1200
7
Nonexistent
85
150
Existent
Invention
The results given in Table 1 show that the target 1 of the present invention in which the complex oxide phase of Al6Si2O13 was formed in the base has a higher density and strength and does not give cracks upon sputtering as compared to the conventional target 1 in which the complex oxide phase of Al6Si2O13 was not formed in the base, even if both had the same composition.
The HfO2 powder, amorphous SiO2 powder, crystalline SiO2 powder, and Al2O3 powder were weighed to give the composition shown in Table 2 and uniformly mixed by a Henschel mixer. Subsequently, the mixed powder was press-molded, after which the obtained molded body was baked under the conditions given in Table 2, thereby producing an inventive target 2 and a conventional target 2, both of which had a diameter of 200 mm and a thickness of 6 mm and included 30% of HfO2, and 20% of SiO2, and the remainders containing Al2O3. The cross sections of the target 2 of the present invention and the conventional target 2 were polished and observed through X-ray diffraction and an electron probe micro analyzer (EPMA) to determine whether or not a complex oxide phase of Al6Si2O13 was formed in the bases of the targets, the results of which are given in Table 2. Furthermore, the density and flexural strength of the target 2 of the present invention and the conventional target 2 were measured. The results are shown in Table 2.
Then, the produced target 2 of the present invention and the produced conventional target 2 were mounted in a direct current magnetron sputtering system, in a state of being soldered with a water-cooled backing plate made of oxygen-free copper. First, the inside of the system was evacuated to be 1×10−6 Torr or less using a vacuum air exhauster. Then, an Ar gas was introduced into the system so as to give a pressure of sputtering gas of 1.5×10−3 Torr. A polycarbonate substrate with a thickness of 0.6 mm was disposed at an interval of 70 mm, i.e., the interval of the targets. In this state, direct current power, i.e., a sputtering power of 7 kW which was higher than norm, was applied, and protective films for an optical recording medium, having a thickness of 50 nm, were formed on a surface of the polycarbonate substrate, using the target 2 of the invention and the conventional target 2, respectively. Here, observation to determine whether or not cracks are formed in the targets was made. The results of which are shown in Table 2.
TABLE 2
Existence or
Properties of Target
Nonexistence
Existence or
Conditions of Baking
of Complex
Nonexistence
Composition of Raw Powder (mol %)
Tem-
Keeping
Oxide of
Flexural
of Cracks
Amorphous
Crystalline
perature
Time
Al6Si2O13 in
Density
Strength
during
Target
HfO2
SiO2
SiO2
Al2O3
Atmosphere
(° C.)
(h)
Target Base
(%)
(MPa)
Sputtering
Present
2
30
20
—
Remainder
oxygen
1400
7
Existent
97
220
Nonexistent
Invention
Conventional
2
30
—
20
Remainder
air
1200
7
Nonexistent
85
145
Existent
Invention
The results given in Table 2 show that the target 2 of the present invention in which the complex oxide phase of Al6Si2O13 was formed in the base has a higher density and strength and does not give cracks upon sputtering as compared to the conventional target 2 in which the complex oxide phase of Al6Si2O13 was not formed in the base, even if both had the same composition.
The stabilizer ZrO2 powder containing 3 mol % of Y2O3, amorphous SiO2 powder, crystalline SiO2 powder, and Al2O3 powder were weighed to give the composition given in Table 3 and uniformly mixed by a Henschel mixer. Subsequently, the mixed powder was press-molded, after which the obtained molded body was baked under the conditions given in Table 3, thereby producing a target 3 of the present invention and a conventional target 3, both of which had a diameter of 200 mm and a thickness of 6 mm and included 30% of ZrO2, and 0.9% of Y2O3, 20% of SiO2, and the remainders containing Al2O3. The cross sections of the target 3 of the present invention and the conventional target 3 were polished and observed through X-ray diffraction and an electron probe micro analyzer (EPMA) to determine whether or not a complex oxide phase of Al6Si2O13 was formed in the bases of the targets, the results of which are given in Table 3. Furthermore, the density and flexural strength of the target 3 of the present invention and the conventional target 3 were measured. The results are shown in Table 3.
Then, the produced target 3 of the present invention and the produced conventional target 3 were mounted in a direct current magnetron sputtering system, in a state of being soldered with a water-cooled backing plate made of oxygen-free copper. First, the inside of the system was evacuated to be 1×10−6 Torr or less using a vacuum air exhauster. Then, an Ar gas was introduced into the system so as to give a pressure of sputtering gas of 1.5×10−3 Torr. A polycarbonate substrate with a thickness of 0.6 mm was disposed at an interval of 70 mm, i.e., the interval of the targets. In this state, a direct current power, i.e., a sputtering power of 9 kW which was higher than the norm, was applied, and protective films for an optical recording medium, having a thickness of 50 nm, were formed on the polycarbonate substrate, using the target 3 of the present invention and the conventional target 3, respectively. Here, observation to determine whether or not cracks are formed in the targets was made. The results of which are shown in Table 3.
TABLE 3
Composition of Raw Powder (mol %)
Existence or
Properties of Target
Stabilizer
Conditions of Baking
Nonexistence
Existence or
ZrO2
Tem-
of Complex
Nonexistence
Containing
pera-
Keeping
Oxide of
Flexural
of Cracks
3 mol % of
Amorphous
Crystalline
Atmos-
ture
Time
Al6Si2O13 in
Density
Strength
during
Target
Y2O3
SiO2
SiO2
Al2O3
phere
(° C.)
(h)
Target Base
(%)
(MPa)
Sputtering
Present
3
30
20
—
Remainder
oxygen
1400
7
Existent
99
280
Nonexistent
Invention
Conventional
3
30
—
20
Remainder
air
1200
7
Nonexistent
92
200
Existent
Invention
The results given in Table 3 show that the target 3 of the present invention in which the complex oxide phase of Al6Si2O13 was formed in the base has a higher density and strength and does not give upon sputtering as compared to the conventional target 3 in which the complex oxide phase of Al6Si2O13 was not formed in the base, even if both had the same composition.
The ZrO2 powder, amorphous SiO2 powder, crystalline SiO2 powder, and La2O3 powder were weighed to give the composition given in Table 4 and uniformly mixed by a Henschel mixer. Subsequently, the mixed powder was press-molded, after which the obtained molded body was baked under the conditions given in Table 4, thereby producing a target 4 of the present invention and a conventional target 4, both of which had a diameter of 200 mm and a thickness of 6 mm and included 30% of ZrO2, and 20% of SiO2, and remainders containing La2O3. The cross sections of the target 4 of the present invention and the conventional target 4 were polished and observed through X-ray diffraction and an electron probe micro analyzer (EPMA) to determine whether or not a complex oxide phase of La2SiO5 was formed in the bases of the targets. The results of which are given in Table 4. Furthermore, the density and flexural strength of the target 4 of the present invention and the conventional target 4 were measured. The results are shown in Table 4.
Then, the produced target 4 of the present invention and the produced conventional target 4 were mounted in a direct current magnetron sputtering system, in a state of being soldered with a water-cooled backing plate made of oxygen-free copper. First, the inside of the system was evacuated to be 1×10−6 Torr or less using a vacuum air exhauster. Then, an Ar gas was introduced into the system so as to give a pressure of sputtering gas of 1.5×10−3 Torr. A polycarbonate substrate with a thickness of 0.6 mm was disposed at an interval of 70 mm, i.e., the interval of the targets. In this state, a direct current power, i.e., a sputtering power of 9 kW which was higher than the norm, was applied, and protective films for an optical recording medium, having a thickness of 50 nm, were formed on a surface of the polycarbonate substrate, using the target 4 of the present invention and the conventional target 4, respectively. Here, observation to determine whether or not cracks are formed in the targets was made. The results of which are shown in Table 4.
TABLE 4
Existence or
Properties of Target
Conditions of Baking
Nonexistence
Existence or
Tem-
of Complex
Nonexistence
Composition of Raw Powder (mol %)
pera-
Oxide of
Flexural
of Cracks
Amorphous
Crystalline
ture
Keeping
La3SiO5 in
Density
Strength
during
Target
ZrO2
SiO2
SiO2
La2O3
Atmosphere
(° C.)
Time (h)
Target Base
(%)
(MPa)
Sputtering
Present
4
30
20
—
Remainder
oxygen
1400
7
Existent
95
190
Nonexistent
Invention
Conventional
4
30
—
20
Remainder
air
1200
7
Nonexistent
85
110
Existent
Invention
The results given in Table 4 show that the target 4 of the present invention in which the complex oxide phase of La2SiO5 was formed in the base has a higher density and strength and does not give cracks upon sputtering as compared to the conventional target 4 in which the complex oxide phase of La2SiO5 was not formed in the base, even if both had the same composition.
The HfO2 powder, amorphous SiO2 powder, crystalline SiO2 powder, and La2O3 powder were weighed to give the composition given in Table 5 and uniformly mixed by a Henschel mixer. Subsequently, the mixed powder was press-molded, after which the obtained molded body was baked under the conditions given in Table 5, thereby producing a target 5 of the present invention and a conventional target 5, both of which had a diameter of 200 mm and a thickness of 6 mm and included 30% of HfO2, and 20% of SiO2, and the remainders containing La2O3. The cross sections of the target 5 of the present invention and the conventional target 5 were polished and observed through X-ray diffraction and an electron probe micro analyzer (EPMA) to determine whether or not a complex oxide phase of La2SiO5 was formed in the bases of the targets. The results of which are given in Table 5. Furthermore, the density and flexural strength of the target 5 of the present invention and the conventional target 5 were measured. The results of which are shown in Table 5.
Then, the produced target 5 of the present invention and the produced conventional target 5 were mounted in a direct current magnetron sputtering system, in a state of being soldered with a water-cooled backing plate made of oxygen-free copper. First, the inside of the system was evacuated to be 1×10−6 Torr or less using a vacuum air exhauster. Then, an Ar gas was introduced into the system so as to give a pressure of sputtering gas of 1.5×10−3 Torr. A polycarbonate substrate with a thickness of 0.6 mm was disposed at an interval of 70 mm, i.e., the interval of the targets. In this state, a direct current power, i.e., a sputtering power of 7 kW which was higher than the norm, was applied, and protective films for an optical recording medium, having a thickness of 50 nm, were formed on a surface of the polycarbonate substrate, using the target 5 of the present invention and the conventional target 5, respectively. Here, observation to determine whether or not cracks are formed in the targets was made. The results of which are shown in Table 5.
TABLE 5
Existence or
Properties of Target
Conditions of Baking
Nonexistence
Existence or
Tem-
of Complex
Nonexistence
Composition of Raw Powder (mol %)
pera-
Oxide of
Flexural
of Cracks
Amorphous
Crystalline
ture
Keeping
La3SiO5 in
Density
Strength
during
Target
HfO2
SiO2
SiO2
La2O3
Atmosphere
(° C.)
Time (h)
Target Base
(%)
(MPa)
Sputtering
Present
5
30
20
—
Remainder
oxygen
1400
7
Existent
98
180
Nonexistent
Invention
Conventional
5
30
—
20
Remainder
air
1200
7
Nonexistent
85
100
Existent
Invention
The results given in Table 5 show that the target 5 of the present invention in which the complex oxide phase of La2SiO5 was formed in the base has a higher density and strength and does not give cracks upon sputtering as compared to the conventional target 5 in which the complex oxide phase of La2SiO5 was not formed in the base, even if both had the same composition.
The stabilizer ZrO2 powder containing 3 mol % of Y2O3, amorphous SiO2 powder, crystalline SiO2 powder, and La2O3 powder were weighed to give the composition shown in Table 6 and uniformly mixed by a Henschel mixer. Subsequently, the mixed powder was press-molded, after which the obtained molded body was baked under the condition given in Table 6, thereby producing a target 6 of the present invention and a conventional target 6, both of which had a diameter of 200 mm and a thickness of 6 mm and included 30% of ZrO2, and 0.9% of Y2O3, 20% of SiO2 and the remainders containing La2O3. The cross sections of the target 6 of the present invention and the conventional target 6 were polished and observed through X-ray diffraction and an electron probe micro analyzer (EPMA) to determine whether or not a complex oxide phase of La2SiO5 was formed in the bases of the targets. The results of which are given in Table 6. Furthermore, the density and flexural strength of the target 6 of the present invention and the conventional target 6 were measured. The results are shown in Table 6.
Then, the produced target 6 of the present invention and the produced conventional target 6 were mounted in a direct current magnetron sputtering system, in a state of being soldered with a water-cooled backing plate made of oxygen-free copper. First, the inside of the system was evacuated to be 1×10−6 Torr or less using a vacuum air exhauster. Then, an Ar gas was introduced into the system so as to give a pressure of sputtering gas of 1.5×10−3 Torr. A polycarbonate substrate with a thickness of 0.6 mm was disposed at an interval of 70 mm, i.e., the interval of the targets. In this state, a direct current power, i.e., a sputtering power of 9 kW which was higher than the norm, was applied, and protective films for an optical recording medium, having a thickness of 50 nm, were formed on a surface of the polycarbonate substrate, using the target 6 of the present invention and the conventional target 6, respectively. Here, observation to determine whether or not cracks are formed in the targets was made. The results of which are shown in Table 6.
TABLE 6
Existence or
Composition of Raw Powder (mol %)
Nonexistence
Properties of Target
Stabilizer
Conditions of Baking
of Complex
Existence or
ZrO2
Tem-
Oxide of
Nonexistence
Containing
pera-
Keeping
La3SiO5
Flexural
of
3 mol
Amorphous
Crystalline
Atmos-
ture
Time
in Target
Density
Strength
Cracks during
Target
% of Y2O3,
SiO2
SiO2
La2O3
phere
(° C.)
(h)
Base
(%)
(MPa)
Sputtering
Present
6
30
20
—
Remainder
oxygen
1400
7
Existent
96
220
Nonexistent
Invention
Conventional
6
30
—
20
Remainder
air
1200
7
Nonexistent
89
145
Existent
Invention
The results given in Table 6 show that the target 6 of the present invention in which the complex oxide phase of La2SiO5 was formed in the base has a higher density and strength and does not give cracks upon sputtering as compared to the conventional target 6 in which the complex oxide phase of La2SiO5 was not formed in the base, even if both had the same composition.
The ZrO2 powder, amorphous SiO2 powder, crystalline SiO2 powder, and In2O3 powder were weighed to give the composition shown in Table 7 and uniformly mixed by a Henschel mixer. Subsequently, the mixed powder was press-molded, after which the obtained molded body was baked under the condition given in Table 7, thereby producing a target 7 of the present invention and a conventional target 7, both of which had a diameter of 200 mm and a thickness of 6 mm and included 30% of ZrO2, and 20% of SiO2, and the remainders containing In2O3. The cross sections of the target 7 of the present invention and the conventional target 7 were polished and observed through X-ray diffraction and an electron probe micro analyzer (EPMA) to determine whether or not a complex oxide phase of In2Si2O7 was formed in the bases of the targets. The results of which are given in Table 7. Furthermore, the density and flexural strength of the target 7 of the present invention and the conventional target 7 were measured. The results of which are shown in Table 7.
Then, the produced target 7 of the present invention and the produced conventional target 7 were mounted in a direct current magnetron sputtering system, in a state of being soldered with a water-cooled backing plate made of oxygen-free copper. First, the inside of the system was evacuated to be 1×10−6 Torr or less using a vacuum air exhauster. Then, an Ar gas was introduced into the system so as to give a pressure of sputtering gas of 1.5×10−3 Torr. A polycarbonate substrate with a thickness of 0.6 mm was disposed at an interval of 70 mm, i.e., the interval of the targets. In this state, a direct current power, i.e., a sputtering power of 9 kW which was higher than the norm, was applied, and protective films for an optical recording medium, having a thickness of 50 nm, were formed on a surface of the polycarbonate substrate, using the target 7 of the present invention and the conventional target 7, respectively. Here, observation to determine whether or not cracks are formed in the targets was made. The results of which are shown in Table 7.
TABLE 7
Properties of Target
Conditions of Baking
Existence or
Existence or
Tem-
Nonexistence of
Nonexistence
Composition of Raw Powder (mol %)
pera-
Keeping
Complex Oxide
Flexural
of Cracks
Amorphous
Crystalline
ture
Time
of In2Si2O7 in
Density
Strength
during
Target
ZrO2
SiO2
SiO2
In2O3
Atmosphere
(° C.)
(h)
Target Base
(%)
(MPa)
Sputtering
Present
7
30
20
—
Remainder
oxygen
1400
7
Existent
99
255
Nonexistent
Invention
Conventional
7
30
—
20
Remainder
air
1200
7
Nonexistent
90
150
Existent
Invention
The results given in Table 7 show that the target 7 of the present invention in which the complex oxide phase of In2Si2O7 was formed in the base has a higher density and strength and does not give cracks upon sputtering as compared to the conventional target 7 in which the complex oxide phase of In2Si2O7 was not formed in the base, even if both had the same composition.
The HfO2 powder, amorphous SiO2 powder, crystalline SiO2 powder, and In2O3 powder were weighed to give the composition shown in Table 8 and uniformly mixed by a Henschel mixer. Subsequently, the mixed powder was press-molded, after which the obtained molded body was baked under the conditions given in Table 8, thereby producing a target 8 of the present invention and a conventional target 8, both of which had a diameter of 200 mm and a thickness of 6 mm and included 30% of HfO2, and 20% of SiO2, and the remainders containing In2O3. The cross sections of the target 8 of the present invention and the conventional target 8 were polished and observed through X-ray diffraction and an electron probe micro analyzer (EPMA) to determine whether or not a complex oxide phase of In2Si2O7 was formed in the bases of the target. The results of which are given in Table 8. Furthermore, the density and flexural strength of the target 8 of the present invention and the conventional target 8 were measured. The results are shown in Table 8.
Then, the produced target 8 of the present invention and the produced conventional target 8 were mounted in a direct current magnetron sputtering system, in a state of being soldered with a water-cooled backing plate made of oxygen-free copper. First, the inside of the system was evacuated to be 1×10−6 Torr or less using a vacuum air exhauster. Then, an Ar gas was introduced into the system so as to give a pressure of sputtering gas of 1.5×10−3 Torr. A polycarbonate substrate with a thickness of 0.6 mm was disposed at an interval of 70 mm, i.e., the interval of the targets. In this state, a direct current power, i.e., a sputtering power of 7 kW which was higher than the norm, was applied, and protective films for an optical recording medium, having a thickness of 50 nm, were formed on a surface of the polycarbonate substrate, using the target 8 of the present invention and the conventional target 8, respectively. Here, observation to determine whether or not cracks are formed in the targets was made. The results of which are shown in Table 8.
TABLE 8
Existence or
Properties of Target
Conditions of Baking
Nonexistence
Existence or
Tem-
of Complex
Nonexistence
Composition of Raw Powder (mol %)
pera-
Oxide of
Flexural
of Cracks
Amorphous
Crystalline
ture
Keeping
In2Si2O7 in
Density
Strength
during
Target
HfO2
SiO2
SiO2
In2O3
Atmosphere
(° C.)
Time (h)
Target Base
(%)
(MPa)
Sputtering
Present
8
30
20
—
Remainder
oxygen
1400
7
Existent
98
200
Nonexistent
Invention
Conventional
8
30
—
20
Remainder
air
1200
7
Nonexistent
90
150
Existent
Invention
The results given in Table 8 show that the target 8 of the present invention in which the complex oxide phase of In2Si2O7 was formed in the base has a higher density and strength and does not give cracks upon sputtering as compared to the conventional target 8 in which the complex oxide phase of In2Si2O7 was not formed in the base, even if both had the same composition.
The stabilizer ZrO2 powder containing 3 mol % of Y2O3, amorphous SiO2 powder, crystalline SiO2 powder, and In2O3 powder were weighed to give the composition shown in Table 9 and uniformly mixed by a Henschel mixer. Subsequently, the mixed powder was press-molded, after which the obtained molded body was baked under the condition given in Table 9, thereby producing a target 9 of the present invention and a conventional target 9, both of which had a diameter of 200 mm and a thickness of 6 mm and included 30% of ZrO2, 0.9% of Y2O3, and 20% of SiO2 and the remainders containing In2O3. The cross sections of the target 9 of the present invention and the conventional target 9 were polished and observed through X-ray diffraction and an electron probe micro analyzer (EPMA) to determine whether or not a complex oxide phase of In2Si2O7 was formed in the bases of the targets. The results of which are given in Table 9. Furthermore, the density and flexural strength of the target 9 of the present invention and the conventional target 9 were measured. The results are shown in Table 9.
Then, the produced target 9 of the present invention and the produced conventional target 9 were mounted in a direct current magnetron sputtering system, in a state of being soldered with a water-cooled backing plate made of oxygen-free copper. First, the inside of the system was evacuated to be 1×10−6 Torr or less using a vacuum air exhauster. Then, an Ar gas was introduced into the system so as to give a pressure of sputtering gas of 1.5×10−3 Torr. A polycarbonate substrate with a thickness of 0.6 mm was disposed at an interval of 70 mm, i.e., the interval of the targets. In this state, a direct current power, i.e., a sputtering power of 9 kW which was higher than the norm, was applied, and protective films for an optical recording medium, having a thickness of 50 nm, were formed on a surface of the polycarbonate substrate, using the target 9 of the present invention and the conventional target 9, respectively. Here, observation to determine whether or not cracks are formed in the targets was made. The results of which are shown in Table 9.
TABLE 9
Existence or
Composition of Raw Powder (mol %)
Nonexistence
Properties of Target
Stabilizer
Conditions of Baking
of
Existence or
ZrO2
Tem-
Complex Oxide
Nonexistence
Containing
pera-
Keeping
of In2Si2O7
Flexural
of
3 mol
Amorphous
Crystalline
Atmos-
ture
Time
in Target
Density
Strength
Cracks upon
Target
% of Y2O3,
SiO2
SiO2
In2O3
phere
(° C.)
(h)
Base
(%)
(MPa)
Sputtering
Present
9
30
20
—
Remainder
oxygen
1400
7
Existent
99
255
Nonexistent
Invention
Conventional
9
30
—
20
Remainder
air
1200
7
Nonexistent
90
150
Existent
Invention
The results given in Table 9 show that the target 9 of the present invention in which the complex oxide phase of In2Si2O7 was formed in the base has a higher density and strength and does not give cracks upon sputtering as compared to the conventional target 9 in which the complex oxide phase of In2Si2O7 was not formed in the base, even if both had the same composition.
As described above, a target for forming a protective film for an optical recording medium according to the present invention can be formed in a large size due to even more improved strength. Moreover, as cracks do not form in the target even under high-power sputtering, a protective film for an optical recording medium can be formed more efficiently. Accordingly, the present invention is substantially useful for industrial applications.
Sasaki, Hayato, Zhang, Shoubin, Mishima, Akifumi, Komiyama, Shozo
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| Nov 27 2008 | KOMIYAMA, SHOZO | Mitsubishi Materials Corporation | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 021931 | /0800 | |
| Nov 27 2008 | MISHIMA, AKIFUMI | Mitsubishi Materials Corporation | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 021931 | /0800 |
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